The term "label" is used herein for convenience but it is to be understood that sheet or film material other than labels may be used, e.g., for decorative purposes, for reinforcement of containers, etc.
Also the term "container" is used herein for convenience but it will be understood that other articles having the same geometric configuration may be employed.
It is known to apply labels to containers by the following procedure: A continuous strip of label material is supplied continuously to a rotating vacuum drum; individual labels are severed from the strip before they are deposited on the vacuum drum or preferably just after the leading end of a label is deposited on the surface of the drum; the vacuum drum rotates each label in turn past a glue applicator, or past a solvent applicator, which applies glue to one or both ends of the label or applies a solvent which is absorbed by the label material and forms an adhesive material in situ; and each label, in turn, is transported to a label applying station where it is released. Meanwhile containers or other articles to which the labels are to be applied are conveyed continuously to the label applying station; the leading end of each label is adhered to a container by glue or other adhesive; the container is caused to spin about its longitudinal axis whereby the label is wrapped around it and the trailing end of the label is adhered directly to the container or to the overlapped portion of the leading end of the label and is adhesively secured thereto. During this label application the container is confined and is spun between solid surfaces, one or both of which may be resilient. The labeled container may be caused to continue spinning after label application, for example, between a pad and a moving belt to smooth the label and attach it more securely to the container.
Such a method is described in U.S. Pat. No. 4,500,386 together with suitable apparatus for carrying out the method.
Other methods and apparatus may be used. For example, precut labels may be supplied from a stack of the same; a turret type of machine such as described in U.S. Pat. No. 4,108,709 may be used, etc.
It is common to use labels of heat shrinkable material, to apply the labels to containers as described above and to apply heat to the label on the container to shrink the projecting edges of the label onto sloping or contoured portions of the container as described in U.S. Pat. No. 4,704,173 and to produce an article such as described in U.S. Pat. No. 4,844,957. Such heat shrinkable labels may be made of polystyrene, polypropylene, polyvinyl chloride, polyethylene and blends of such materials. Also the labels may be laminated. Such label materials are well known in the art.
Difficulties are, however, encountered in this procedure where the surface to be labeled with a heat shrinkable label is convex in shape. For example, the classic Coca-Cola bottle has a shape as follows: The lower part is fluted, the upper part (below the neck) is also fluted and between the two fluted areas is a convex portion or sector which it is desired to label. If a non-heat shrinkable label is applied to this surface, difficulties are encountered in conforming the label to the convex surface. This difficulty can be alleviated by applying a heat shrinkable label to the convex surface at its greatest diameter (i.e., furthest from the vertical axis of the bottle), then shrinking it onto the convex surface. However it is difficult to apply the label initially to the convex sector and it is also difficult to shrink the label, after it has been initially applied, onto the convex sector in a proper manner so as to present a neat, pleasing appearance.